<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Vue</title>
</head>
<body>
<!--第一步，导入Vue.js-->
<script src="https://cdn.jsdelivr.net/npm/vue@2.6.14/dist/vue.js"></script>
<div id="app">
    下拉框：
    <select v-model="selected">
        <option disabled value="">请选择</option>
        <option>A</option>
        <option>B</option>
        <option>C</option>
    </select>
    <span>选中的值：{{selected}}</span>
</div>
<script>
    var vm = new Vue({
       el: "#app",
       data: {
           selected: ''
       }
    });
</script>


</body>
</html>